Computing - Little Man Computer
AQA Computer Science 2022
Input and storing
Instruction format
Store
Arithmetic instructions
What does the ADD instruction do in LMC?
ADD instruction do in LMC?Add what is in the address given to the accumulator.
What does the SUB instruction do in LMC?
SUB instruction do in LMC?Subtract what is in the address from the accumulator.
Output and halting
Branching instructions
What does BRZ do in LMC?
BRZ do in LMC?If the contents of the accumulator is 0, set the program counter to the given address.
What does BRP do in LMC?
BRP do in LMC?If the contents of the accumulator is 0 or positive, set the program counter to the given address.
Data and addressing
What does DAT do in LMC?
DAT do in LMC?Instead of storing the instruction in RAM, store the operand given where that operation would be.
What is the program counter in LMC?
It holds the address of the next instruction the little man has to carry out.
What is direct addressing?
Where an operand is specified as a memory address holding the value to be used.
What is immediate addressing?
Where the operand is specified as the actual value explicitly.
Why is it called Little Man Computer?
Because it’s like a little man running about, grabbing instructions and doing all the operations in a computer.